Esophageal cancer is a common malignancy in the United States and worldwide. A number of studies indicate that the molecular basis of esophageal squamous cell carcinoma (ESCC) involves the activation of oncogenes and inactivation of tumor suppressor Genes, but the underlying molecular mechanisms remain elusive. In particular, how specific genetic alterations contribute to the development of ESCC is unclear. A critical genetic event in the molecular pathogenesis of ESCC is epidermal growth factor (EGFR) overexpression. We have overexpressed EGFR through retrovirally-mediated transduction in primary human esophageal epithelial cells that were established in a joint collaboration between Dr. Herlyn.s lab and our lab. This has led to observations of coordinated actions of enhanced cell migration modulated by EGFR. In addition, when EGFR overexpressing primary human esophageal epithelial cells are placed in a novel organotypic cell culture system, there is induction of increased epithelial thickness (hyperplasia) with hyperproliferation. We have also developed a novel and unique transgenic mouse model in which the EGFR oncogene is targeted to the esophageal squamous epithelium by employing the Epstein-Barr virus ED-L2 promoter. This promoter has been shown by us to be active in basal and suprabasal cells of esophageal keratinocytes. The work described in this Project is designed to focus on the role of EGFR in esophageal carcinogenesis. Our hypothesis is that EGFR plays critical roles in the very early stages of esophageal squamous carcinogenesis through the promoting hyperproliferation and cell migration. The objectives will be achieved through the following interrelated Specific Aims: (1) To determine the functional activation of Akt by EGFR and determine the possible link between upregulation of STAT-1 and MMP-1 as modulators of cell migration; (2) To elucidate the role of RAD, a ras-like GTP binding protein, that is induced by EGFR and may modulate increased cell proliferation; and (3) To assess the functional consequences of EGFR overexpression in transgenic mice and compound mice (EGFR transgenic mice are crossbred with transgenic mice where dominant negative p53 is expressed in esophageal epithelial cells). In aggregate, the molecular, biochemical and functional aspects of EGFR will be defined in esophageal squamous carcinogenesis through these innovative model systems and important interactions with other projects. Additionally, the outlined investigations will employ the Core facilities.